Question

Synapse function prompt:

You are talking with your 10 year old nephew who is very excited to tell you that he learned in science class that the nervous system is like a series of electrical wires that run throughout the body. With your newfound experience in physiology you know that’s not quite true, and that there are gaps (synapses) between neurons, meaning information in the nervous system is not just transmitted via action potential. Describe to your nephew how information is passed from the pre-synaptic to post-synaptic neuron in order to allow information flow throughout the nervous system.

Answer 1

Answer) Passage of information from presynaptic neuron to postsynaptic neuron -

A nerve impulse is transmitted from one neuron (presynaptic neuron) to another neuron (postsynaptic neuron through junctions called synapses.

A chemical synapse is formed by the membrane of a presynaptic and a postsynaptic neuron, which are separated by a fluid filled space called synaptic cleft.

Chemicals called neurotransmitters are involved in the transmission of impulses at these impulses.

The axon terminals contain vesicles (boutons) filled with these neurotransmitters.

When an impulse (action potential) arrives at the axon terminal, it depolarizes the membrane opening voltage gated calcium channels.

Calcium ions stimulate the movement of the synaptic vesicles towards the membrane where they fuse with the plasma membrane and release their neurotransmitters in the synaptic cleft by exocytosis.

The released neurotransmitters bind to their specific receptors present on the postsynaptic membrane.

Acetylcholine is the most common neurotransmitter.

Acetylcholine attaches to nicotinic acetylcholine receptors on postsynaptic membrane and increases the permeability of postsynaptic membrane to sodium ions (mainly) and other positive ions.

Increased permeability of sodium ions causing depolarization of the postsynaptic membrane causing generation of action potential.